When we are considering the Bible’s teaching on a subject, we must consider precisely that: the Bible’s teaching. It is never adequate, and usually it is treacherous, to simply consider the New Testament in isolation. In the subject before us in these handful of articles (the question of why I believe that the Bible teaches me I should have my children baptised), this principle is reinforced within the Bible itself. In a number of places, where NT writers address the issue of baptism, they do so by explicitly drawing on OT precedent. They clearly see a profound degree of continuity between the sacramental life of the Church in the Old and New Testaments. We’ll look at these passages in due course, but for now I’d like to begin to focus on the covenant God made with Abraham. To my mind this is foundational, in large part because it remains the covenant through which we are saved.
We find the Apostles teaching that all those who are saved through Christ, are children of Abraham – whether they are ethnically Jew or Gentile. The covenant made with Abraham was designated an ‘everlasting covenant’ (Gen.17:7) in which God declared that He would be the God of Abraham - and of his descendants after him. Those with whom the covenant was cut would claim the blessings of the covenant by expressing faith in God’s provision, as Abraham had done (Gen.15:6). In this way, all nations will be blessed through Abraham (Gen.12:3). What then is the connection between these early chapters of Genesis and our current experience of Church? Paul – following Jesus – makes the connection for us in Galatians 3: Understand then that those who believe [in Christ] are children of Abraham … those who have faith are blessed along with Abraham, the man of faith (v.7-9). Indeed Paul goes further: there is no other way to be saved than through the covenant with Abraham. ‘Christ redeemed us in order that the blessing given to Abraham might come to the Gentiles through Christ Jesus, so that by faith we might receive the promise of the Spirit (Gal.3:14). By virtue of our being a Christian Church, St. John’s is folded into the covenant that God cut with Abraham through redemption by Christ. ‘If you belong to Christ, then you are Abraham’s seed, and heirs according to the promise (Gal.3:29).
But what does all this have to do with baptism? The question focusses on the sign of the covenant given to Abraham in Genesis 17 – or rather, the question of how the sign of the covenant functions. God Almighty (17:2 – and notice that it is the LORD who does all the talking) binds Himself to Abraham and his descendants through a covenant which is to be articulated through and signified by circumcision. Why? Because Christians in the OT are looking forward to, and their faith is based on, the future work of the Seed / Offspring of Abraham (i.e. Christ, see Gen.3:15), who will Himself be cut off (i.e. through the cross).
But how does this sign function? And what is the extent of it? The sign of this covenant was not to be taken by Abraham alone, but by his whole household (Gen.17:23 / Ex.12:48) – even those we know grew up not sharing Abraham’s faith, and so didn’t walk with the LORD (e.g. Ishmael; Esau etc.). Nevertheless, all that Abraham has is to be devoted to the Lord. As we mentioned last week, the head of the family represents the family to God, and commits them to the worship of Him. Throughout the following generations the children of Abraham were to be marked by the sign of the covenant at 8 days old. In so doing they are associated with the company of those who are marked out by the Covenant the LORD has cut; sealed (Rom.4:11) with a visible pledge that the Author will honour what He has covenanted to do when the conditions it describes are met. Their circumcision – like all covenant signs/seals – cuts in both directions. There are no neutral encounters with the LORD – whether in Word or Sacrament. They will always result in blessing or sanction. The message of this sacrament is clear. Look in trust to the event that circumcision foretells (the cutting off of the Seed), or you will yourself be cut off from the covenant people. The conditions of belief or unbelief issue in salvation or destruction. This is the message of the sacrament.
As Paul argues in Galatians, the Church continues to be saved, through faith in Christ, in the context of the Abrahamic Covenant. So why are we not circumcised? Because the great moment which circumcision pointed forward to (the cutting off of Christ the Seed through His crucifixion), has been fulfilled. And all that this great moment was designed to achieve has been accomplished. Because of this, the sign and seal of circumcision has been replaced, as the prophets foretold generations before. It has been replaced with a new sign that points to what the death of Christ has achieved for His covenant people: the pouring out of the Holy Spirit. “I will sprinkle clean water on you and you will be clean. I will cleanse you from all you impurities and from your idols. I will give you a new heart and put a new Spirit in you; I will remove from you your heart of stone, and give you a heart of flesh. And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws. You will live in the land I gave your forefathers; you will be my people, and I will be your God. I will save you from all your uncleanness” (Ezek.36:25-28). To this we will turn next time.
 It should be noted that the effectiveness of baptism, like any means of grace (such as preaching or communion) is neither automatically guaranteed, nor necessarily limited to the time of its celebration.
 As one theologian, Louis Berkhof puts it: It was natural when the real Lamb of God made His appearance and was on the point of being slain, the symbol and the type should disappear. The all-sufficient sacrifice of Jesus Christ rendered all further shedding of blood unnecessary and therefore it is entirely fitting that the bloody element should make way for the unbloody. Systematic Theology, p.647